Medical acupuncture, also known as dry needling, is a widely used treatment in the physical therapy field. It started to gain acceptance in our field in the 1980s and has grown in popularity since.

Its increase in use has resulted in an exponential rise in research papers investigating its effectiveness. Using the PubMed database, the search term "dry needling" yielded one result in the year 2000, seven new papers in 2009 and an astonishing 51 in 2014.

Dry needling is now being taught in many physical therapy schools to entry-level students, rather than being a post-graduate continuing development course as it was more than 10 years ago.

Why such a big increase in popularity?

"Both patient acceptance and the demonstration that this technique has 'evidence-based procedure' data for conditions like upper-quarter myofascial pain, where both immediate reduction of pain (grade A), and reduction of pain at four weeks (grade A), have been demonstrated," according to physical therapists John S. Halle and Rob J. Halle.

So more and more of us, as therapists, are using acupuncture in treating our clients. We have seen its benefits in treating myofascial pain conditions. For the most part, the clients like it, too. Most have positive experiences of acupuncture.

But there will always be clients who want to know more — either simply out of curiosity or due to concerns surrounding the use of needles. So how should a therapist explain to a client, in lay terms, what happens when you insert those needles? What should they expect to feel? How does it help their injury?

When I trained in medical acupuncture recently we were taught it in a scientific language, one that the vast majority of my clients would not understand. I found myself wondering how on earth I was going to explain this to people both accurately and in a way they would understand. So, I've given it some thought and here is my answer.

The science explanation

First off, we have to understand the technicalities. There are four mechanisms which are thought to play a part in acupuncture efficacy. Here is an overview:

1. Localized effects

There are several effects that take place at the site of needle insertion. Firstly, the connective tissue releases ATP, which is then converted to ADP and adenosine. The latter binds to nociceptors on the peripheral nerves and inhibits the signal, resulting in a reduction in pain.

Secondly, the adenosine also binds to the epithelium of the blood vessels and induces nitrous O2 which is a potent vasodilator, therefore increasing blood supply.
This is increased further if a local twitch response is elicited as there is a release of calcitonin gene-related peptide (CGRP), another powerful vasodilator.

2. Segmental analgesia

When the needle is inserted, information is transmitted up the nerve that supplies the area. Mediation of A-delta fibers, which then form synapses with inhibitory interneurons within the dorsal horn, results in a suppression of the pain signal.

The segmental inhibition only occurs during needle stimulation. This may explain the analgesic effect of acupuncture on a short-term basis but doesn't explain any prolonged pain relief.

3. Central mechanisms

Stimulation of acupuncture points activates the mechanoreceptors, which transmit afferent signals to the CNS. These signals affect the brain in many ways, including the stimulation of the hypothalamus and activation of the relevant brain nuclei that modulate analgesia.

Furthermore, the activation of descending pain inhibitory systems which involves the release of enkephalins and endorphins, monoamines, GABA and glycine.

4. Diffuse noxious inhibitory control (DNIC)

This is a phenomenon that attempts to explain pain inhibition from acupuncture. It suggests that pain can be inhibited by using a counterirritant (in this case the needle), distant to the source of pain, that activates an intricate system of impulses and responses within the nervous system.

The lay summary

Clearly, the above explanations for acupuncture aren't suitable for the general public who come into most physical therapy clinics. So, we need to find a clear, concise and relatable version to satisfy our clients curiosities.

Let's break it down.

The localized effects come down to pain inhibition and an increase in blood flow. Segmental analgesia again is all about suppression of the pain signal. Central mechanics center around the release of substances including endorphins and serotonin — many people will have heard of these two as "feel-good" chemicals. DNIC, on a basic level, has a similar grounding to the pain-gate theory, which again many people will be at least partially aware of.

My explanation would look something like this

Acupuncture works by causing:

• A large increase in blood flow at the site of the needle, which aids healing
• A release of "feel-good" chemicals such as serotonin and endorphins — natural pain and stress fighters
• Causing an analgesic (or numbing) effect at the site of the needle caused by disruption of the pain signal and providing an alternative stimulant
• Sending signals to the central nervous system, which responds through pain relief and a natural healing response

Safety fears

For those who are concerned about safety issues such as infection risks, pain levels and side effects, the following points can help:

• Acupuncture needles are individually-wrapped, sterile needles that are used once and then disposed of as medical waste.
• Acupuncture needles are approximately 0.25 mm thick — the most commonly used hypodermic needles (for injections, blood tests, etc.) are between 0.8-1.5 mm.
• Most people feel a small prick as the needle is inserted, which may be followed by a muscle twitch and a deep, dull ache. Many people experience no pain at all.
• Side effects are rare. The most common are dizziness or nausea, aching at the site of the needle for a short period afterward and the occasional small bruise.

In my experience, most people are happy to give it a go, especially if they can't see the needles. It is only those with a needle-phobic disposition who may be unwilling to receive acupuncture treatment, even after a full explanation of its benefits.

Always make sure you gain either written consent for acupuncture or that verbal consent is recorded in the patient's clinical notes. It is a good idea to have a fact sheet typed up for patients to read, prior to their treatment. This can cover the benefits, safety aspects, side effects and expected sensations so the patient is fully informed.